3d carving vertical shadow lines

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bsouthnow
Posts: 34
Joined: Wed Feb 10, 2010 3:35 pm

3d carving vertical shadow lines

Post by bsouthnow »

Hey Guys and Gals;
Been awhile since my last post but I just recently retired and want to get back into my art. I recently started carving one of the Aspire standard models for two horses running on a dish style plate. I'm still using Aspire 4 (but hope santa clause brings me an update) and am having difficulties. I'll try to post some pictures but what is happening is on the dish surface I'm seeing some horizontal lines. I've tried a light sand but they are still there. The specifics are Aspire 4.0, Mach 3 Op system, .0625 ball nose tool with a 10% step over at a spindle speed of 20000 and a feed rate of 60. The plate which will be an insert on a wooden box consist of an oval which measures about 5 X 6. I've used both raster and offset machine motions and even though the offset is better it is still there.
My machine is a home brew with precision rails and screws driven by servos. The machine appears to be very rigid and has recently been cleaned and lubricated.
Anyone have any ideas what to try? I'm hoping it is being caused by a setting in Mach but to be honest, I have not a clue.
Any help will be appreciated.
Bill in Spartanburg.
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dealguy11
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Re: 3d carving vertical shadow lines

Post by dealguy11 »

This is pretty much always machine-related, though often difficult to pin down. On one of my prior machines it was due to backlash in one of the axes. You need to check your hold-down, check all the axes for backlash, make sure there is no vibration in the machine setting up a rhythmic movement, etc. etc. On my first machine I was never able to get rid of these lines due to the significant amount of vibration in the machine. Hopefully you can find what's causing it on yours. In the meantime, a good set of scrapers like the Flexcut version with different scraper profiles can help make the current project look better.
Steve Godding
D&S Artistic Woodworking http://www.dsartisticwood.com

ger21
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Re: 3d carving vertical shadow lines

Post by ger21 »

Try doing your finishing cuts along the other axis, at 90°. Looks like some sort of machine vibration or oscillation.
Gerry - http://www.thecncwoodworker.com

bsouthnow
Posts: 34
Joined: Wed Feb 10, 2010 3:35 pm

Re: 3d carving vertical shadow lines

Post by bsouthnow »

Thanks Guys;
I reduced the acceleration a bit to see if that helps. It is most definitely a vibration. I felt is when laying a hand on the z carnage when cutting. Not to find the culprit and correct it. I'll post my results in case it beneficial to other members.
Bill

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scottp55
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Re: 3d carving vertical shadow lines

Post by scottp55 »

Bill,
BEFORE trying it on wood....Just drive it around at various speeds with a hand on the frame....some WILL be smoother...write down the smooth feeds(MY machine hates 1.3IPS on 2 axis moves)
Do the same for Plunge speeds....
Do the same for different RPMs on router spindle....

TRY to use the Sweet feeds and speeds.
Then try 3D cuts "Air Cuts" (rastering along the gantry is usually most stable, as less mass involved)
So long as bit is close to room temp at end of real cut, and cutting CHIPS(however small the chip is)....you have a good combo, and can usually increase feed/speeds proportionally in Sweet Spots until cut quality degrades....and then back off 10% or so until it's at YOUR quality.

Basically just learning YOUR machine :)
Hope the heck it helps in any way!
scott
scott

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